Pending the determination by the Commissioners of any claim for relief in respect of terminal expenses or losses on sales of stock, the Commissioners may make assessments and collect excess profits tax for any chargeable accounting period without reference to the claim and the relief necessary to give effect to the determination of any such claim shall be given by repayment unless it can be set off against excess profits tax for any chargeable accounting period which has been assessed on the person making the claim and remains unpaid.